The present invention relates to a monolithic infrared ray charge transfer element for use in an infrared ray image device.
To realize a charge transfer element operating at infrared-ray wavelengths in a range of 3 to 5 .mu.m, there has presently been developed only one element of the monolithic type, i.e., the so-called monolithic silicon Schottky-type infrared charge transfer element.
On the other hand, for a wavelength range of 8 to 14 .mu.m, which is very important commercially, mercury cadmium telluride (Hg.sub.1-x Cd.sub.x Te: x-0.2) and lead tin telluride (Pb.sub.1-x Sn.sub.x Te: x-0.2) have been considered as important materials since these materials have high sensitivity for infrared in the 8 to 14 .mu.m wavelength range. These materials, however, generally are not stable compared with silicon or gallium arsenide, which have been widely used in the semiconductor industry. Particularly, mercury cadmium telluride is thermally unstable and mechanically very weak. Lead tin telluride has a very high dielectric constant. Therefore, it has been difficult to produce a charge transfer device using either of these materials. Moreover, devices fabricated from either material exhibit poor transfer characteristics. For these reasons, these materials have not been used for monolithic infrared charge transfer elements. Their use generally has been restricted to ordinary, nonmonolithic infrared ray detecting elements.
To realize a charge transfer element using either of these materials, a hybrid combination of an infrared detecting element of mercury cadmium telluride and a charge transfer element fabricated from silicon has been proposed. In such a hybrid combination, however, it is necessary to electrically connect these elements. Techniques for making such connections are very complicated, and may result in a high parasitic capacitance and/or parasitic inductance which adversely affects characteristics of the resultant element.